Sizing agents are used in the papermaking process to increase wood fiber's resistance to liquid penetration. The resistance to the absorption of liquids is desired when the paper product is purposefully wetted during a converting process (printing or laminating) or accidentally wetted (packaging containers or newspapers). Alkenyl succinic anhydride (ASA) is an internal sizing agent, which is commonly used to treat fibers in the papermaking process, making them more hydrophobic. Internal sizing refers to the treatment of the wood fibers prior to forming a wet web. ASA is a water insoluble oil that is essentially nonionic in nature. Therefore, ASA must be emulsified before it is added to the papermaking process. Emulsification of ASA produces an oil in water emulsion and also cationizes the ASA emulsion droplets. Cationizing the ASA droplets helps to promote emulsion stability and aids in ASA retention. Cationic emulsifiers such as derivitized starches and synthetic acrylamide-based polymers are currently used as emulsifiers for ASA.
Despite available technologies, there exists a need to improve sizing performance and machine efficiency in paper production processes. There also exists an ongoing industrial need in the papermaking industry to develop sizing formulations and methods that improve sizing of paper and paperboard and also provide other enhancements to papermaking process to reduce the need for multiple chemistries.